As an image display device substitutable for liquid crystal display (LCD), image display devices with the use of technology such as an electrophoresis method, an electro-chromic method, a thermal method, dichroic-particles-rotary method are proposed. As for these image display device, it is conceivable as inexpensive visual display device of the next generation from a merit having wide field of vision close to normal printed matter, having smaller consumption with LCD, spreading out to a display for portable device, and an electronic paper is expected.
Recently, electrophoresis method is proposed that micro-encapsulate dispersion liquid made up with dispersion particles and coloration solution and dispose the liquid between faced substrates. However, in the electrophoresis method, there is a problem that a response rate is slow by the reason of viscosity resistance because the particles migrate among the electrophoresis solution. Further, there is a problem of lacking imaging repetition stability, because particles with high specific gravity of titanium oxide is scattered within solution of low specific gravity, it is easy to subside, difficult to maintain a stability of dispersion state. Even in the case of microencapsulating, cell size is diminished to a microcapsule level in order to make it hard to appear, however, an essential problem was not overcome at all.
Besides the electrophoresis method using behavior in the solution, recently, a method wherein electro-conductive particles and a charge transport layer are installed in a part of the substrate without using solution is proposed. [The Imaging Society of Japan “Japan Hardcopy '99” (Jul. 21-23, 1999) Transaction Pages 249-252]However, the structure becomes complicated because the charge transport layer and further a charge generation layer are to be arranged. In addition, it is difficult to constantly dissipate charges from the electro-conductive particles, and thus there is a drawback on the lack of stability.
In order to solve the problems mentioned above, as an image display device having rapid response rate due to a dry type display, simple construction, inexpensive cost and excellent stability, it is known an image display device which comprises an image display panel having one or more image display cells isolated each other by partition walls, in which liquid powders composed of a solid material stably floating as a dispersoid in a gas and exhibiting a high fluidity in an aerosol state are sealed between a transparent substrate and an opposed substrate, and, in which the liquid powders, to which an electrostatic field produced by a pair of electrodes having different potentials is applied, are made to fly and move so as to display an image. Moreover, it is known an image display device utilizing normal particles in spite of the liquid powders.
However, in the dry type image display device having the construction mentioned above, a manufacturing method is not generally established, and further it is not established a technique for sealing the particles or the liquid powders equally and uniformly between the substrates, which is an especially important step in the manufacturing method. Here, if the step of sealing the particles or the liquid powders does not satisfy the above conditions, there occur various problems such as a color shading, a chipped image, a variation of image response speed due to an unevenness of distance between the substrates, an increase of driving voltage for flying and moving the particles or the liquid powders and so on.
As a method of sealing the particles (hereinafter, sometimes called as powders) between the substrates, it is conceivable that use is made of a roll coater application method in which the powders are drew out on the substrate and a particle immersion method in which the particles are applied on the substrate by floating the powders in the air by means of agitation, air blow and so on and transferring the substrate in the floating powders. Among them, in the roll coater application method, since it is difficult to adhere the particles to the substrate, it is liable to generate a shortage of filling amount (applying amount) of the particles and a deviation of density. Also, in the particle immersion method, since it is difficult to adhere the particles to the substrate, it is liable to generate a shortage of filling amount of the particles. In addition, since the particles are not firmly secured to the substrate, it is liable to generate a particle flying and a particle deviation due to a shock or a wind pressure when two substrates are stacked. Therefore, both methods are not sufficient for sealing the particles.
Moreover, in the case that a plurality of cells are formed between the substrates in a matrix arrangement by means of a grid spacer serving as the partition walls and two kinds of powders are sealed in respective cells, the particles remain on a top portion of the partition walls. Therefore, when two substrates are stacked, there is a case such that the particles remain in a boundary between the substrate and the partition wall or in a boundary between the partition walls, and thus there is a problem such that a distance between the substrates is node made even. In addition, there is no idea for a method of sealing the liquid powders between the substrates equally and uniformly.
Further, in the dry type image display device having the construction mentioned above, the partition wall arrangement is normally performed by positioning the partition walls between the transparent substrate and the opposed substrate and applying a sealing agent to an outermost peripheral portion of the substrate. In the known manufacturing method mentioned above, the connection between the substrate and the partition wall has a sufficient strength in the case that a glass substrate is used as the transparent substrate and the opposed substrate, but the connection mentioned above does not have a sufficient strength if use is made of the other transparent substrate such as a resin substrate. Furthermore, it is not known the suitable method for forming a module of circuits such as a driver used for an image display.